This invention concerns an optical disk device that has a tracking adjustment system that performs tracking adjustment of an optical pickup with respect to said optical disk in order to read-write information by focusing a light spot from an optical pickup onto the optical disk, a sled adjustment system that adjusts the sled position of said optical pickup, and a control means that controls these adjustment systems. This invention can be used in an optical disk device that regenerates information recorded on, for example, a CD, CD-ROM, DVD, or DVD-ROM and records/regenerates information with respect to a CD-R, CD-RW, DVD-R, or DVD-RW.
Optical disk devices that play (or regenerate) information recorded on a CD, CD-ROM, DVD, DVD-ROM, etc., and optical disk devices that record/play information with respect to a CD-R, CD-RW, DVD-R, DVD-RW, etc. are known. These optical disk devices are constructed so as to record and/or play information by shining a light spot from an optical pickup onto the information recording surface of a mounted optical disk and detecting the reflected light. Such an optical disk device has a tracking adjustment system and sled adjustment system, etc., and the attitude of the optical pickup with respect to the optical disk device is adjusted by outputting control instructions from a control means that controls these systems.
The tracking adjustment system is the part that detects with high precision the information that is recorded on the optical disk by causing the optical pickup to follow the tracks on the optical disk. It has a two-axis adjustment mechanism that adjusts the tilt position and plane direction position of the objective lens that constitutes the optical pickup with respect to the information recording surface of the optical disk, and an actuator that supplies driving force to such two-axis adjustment mechanism.
The sled adjustment system is the part that adjusts the radial-direction position of the optical pickup with respect to the optical disk. It has a mechanism main body having a rack, which extends along the radial direction of the optical disk and on which the optical pickup is mounted, and a toothed wheel that engages with this rack, as well as a stepping motor that causes the toothed wheel to rotate.
In such an optical disk device, in order to cause a track jump operation to be performed to move to the target track by jumping across multiple tracks all at once, first, by means of the tracking adjustment system, one adjusts the attitude of the object lens that constitutes the optical pickup while detecting the tracking error signal output from the optical pickup, and moves the center of the light spot to the target track; next, in correspondence with this, a so-called traverse movement is executed by means of the sled adjustment (system) to bring the optical pickup to immediately below the target track.
Heretofore, the tracking adjustment system and sled adjustment system were set inside the same control digital signal processor (DSP), and control was done in such a way as to keep the speed of the traverse constant by making use of an internal autosequencer and making the tracking adjustment system and the sled adjustment system move in cooperation.
But in an adjustment system in which the tracking adjustment system and the sled adjustment system are thus made to move in cooperation, even when it is necessary to perform tracking adjustment because of a disturbance such as eccentricity of the optical disk, sled adjustment gets done along with it, so there is the problem that the sled adjustment system may reacts oversensitively to eccentricity of the optical disk, etc.
But in a structure in which the tracking adjustment system and the sled adjustment system are thus kept independent, when the aforesaid traverse movement is to be made, it is necessary to first align the center of the light spot on target track for only the tracking system, that is, in a state in which the tracking system does not operate, creating the problem that the farther away the target track is, the narrower the movement-direction field of view of the optical pickup may becomes, making inferiority in detecting the optical disk track.
It is an object of the present invention to provide an optical disk device in which it is possible to overcome above-mentioned problem.
The optical disk device of this invention, in a composition that independently controls the sled adjustment system and tracking adjustment system, accomplishes the aforesaid purpose by detecting the tracking drive signal for driving that is output from the tracking adjustment system, and performing drive control of the sled adjustment system based on such tracking drive signal.
Specifically, the optical disk device of this invention, which is an optical disk device that has a tracking adjustment system that, by shining a light spot from an optical pickup onto an optical disk, adjusts the tracking of said optical pickup with respect to said optical disk in order to do recording and/or playback of information, a sled adjustment system that adjusts the sled position of said optical pickup, as well as a control means that controls these adjustment systems, is characterized in that said sled adjustment system and said tracking adjustment system are controlled independently.
Such disk device has an offset value acquisition means that detects the tracking drive signal for driving that is output from said tracking adjustment system and acquires this signal value as tracking drive offset values, an offset value comparison means that compares the offset center value, which is the tracking drive offset value in the state in which no tracking adjustment control is done, and the offset representative value computed by this offset value acquisition means, a search direction acquisition means that acquires the track search direction of said optical pickup from a control instruction output from said control means and a sled drive decision means that decides whether to drive said sled adjustment system based on the comparison result by said offset value comparison means and the track search direction obtained by said search direction acquisition means.
The sled drive decision means is so as to decide to drive the sled adjustment system (a) if the result by the offset value comparison means is that the tracking drive offset value is greater than or equal to the offset center value and the search direction obtained by the search direction acquisition means is the direction going radially outward on the optical disk, or (b) if the result by the offset value comparison means is that the tracking drive offset value is less than the offset center value and the search direction obtained by the search direction acquisition means is the direction going radially inward on the optical disk.
With an embodiment of the this invention as thus described, by the offset value acquisition means, the tracking drive signal is detected and tracking drive offset signals are acquired, and the tracking drive offset value obtained is compared with the offset center value by the offset value comparison means, so in drive control of the sled adjustment in track search, the adjustment state of the tracking adjustment system can be ascertained.
In addition, whether to drive the sled adjustment system is decided by the sled drive decision means based on the track search direction obtained by the search direction acquisition means and the result obtained by the offset value comparison means, and drive control of the sled adjustment system is done by the control means. Therefore even if the mode is not one in which the tracking adjustment system and the sled adjustment system move in cooperation, traverse movement in track searches can be certainly realized, and because they do not move in cooperation, the sled adjustment system can be prevented from reacting oversensitively together with tracking adjustment.
Furthermore, because the sled drive decision means is constituted so as to decide to drive the sled adjustment system in the above-described cases (a) or (b), the driving of the sled adjustment system is performed only in the case of necessity. That is, with (a) the tracking drive offset value greater than or equal to the offset center value, it is decided that the position of the objective lens in the tracking adjustment system is in a state going radially outward on the optical disk, so if the search direction is radially outward on the optical disk, and further one strengthens the tracking adjustment, then the field of view of the optical pickup will become narrower. Conversely, in the case where the relationship between the tracking drive offset value and the offset center value is as described above, the tilt direction of the objective lens of the optical pickup and the search direction are in a reverse-facing relationship, so even if the traverse movement is continued, the field of view of the optical pickup will not become narrow, and there is no need to perform driving of the sled adjustment system. The case of (b) is in a reverse relationship with the case of (a), i.e., if the tracking drive offset value is less than the offset center value and the search direction is radially outward, then the field of view of the optical pickup will not become narrow, and similarly there will be no need to perform driving of the sled adjustment system.
In the foregoing, it is desirable that the control instruction that is output from the above-described control means to the sled adjustment system be generated based on the difference between the offset center value and the tracking drive offset value in the offset value comparison means.
By thus taking the difference of the two offset values, one can roughly ascertain the tilt, with respect to the optical disk, of the objective lens that constitutes the optical pickup in the tracking adjustment system. Therefore by generating and outputting the control instruction that is output from the control means to the sled adjustment system based on this difference, sufficient sled adjustment can be done to correct the tilt of the objective lens, so by alternately drive-controlling the tracking adjustment system and the sled adjustment system, continuous traverse movement can be realized.
Also, it is desirable that the above-described offset value acquisition means, offset value comparison means, search direction acquisition means, and sled drive decision means be constituted as software expanded in a microcomputer that includes the control means. By thus constituting each means as software expanded in a microcomputer, it is no longer necessary to build into the optical disk device a DSP, etc. especially for sled adjustment, thereby reducing the manufacturing cost of the optical disk device and making it possible to change the control method simply, just by replacing the software when the sled adjustment control method is to be changed.
Also, in the optical disk device of this invention, which is an optical disk device that has a tracking adjustment system that, by shining a light spot from an optical pickup onto an optical disk, performs tracking adjustment of said optical pickup with respect to said optical disk in order to record and/or play information, a sled adjustment system that adjusts the sled position of said optical pickup and a control means that controls these adjustment systems, said sled adjustment system and said tracking adjustment system are controlled independently.
Such device also has a means that detects the tracking drive signal for driving that is output from said tracking adjustment system, a means that detects the tilt, from a basic state, of the objective lens that constitutes said optical pickup based on the values of said detected tracking drive signal, a search direction acquisition means that acquires the track search direction of said optical pickup from a control instruction output from said control means and a means that decides the drive mode of said sled adjustment system based on the tilt of said objective lens from the standard state and said track search direction.